Hi iwishman:
A dreadful situation and one which obviously gives you no peace of mind.
I've read the responses, some of which are useful, some others absolutely ridiculous. If only they were in your situation? I don't think their replies would be so flippant!
Please don't expect miracles from the Police this evening - I'm sure you won't - because this is a very delicate matter for the Police to try to resolve, speaking from personal experience.
Make sure, though, that the subject of an ASBO is mentioned, for this is one answer to such a tricky situation. I'm sure from what I've read that you maybe would settle for a quiet and peaceful co-existence, but it sounds as if that may not be possible.
There's also the possibility of some kind of restraining order against your neighbour but not only might that involve personal expense to yourself, you would also have to amass enough evidence against them to justify it.
The CAB has been mentioned and they are able to provide free legal advice.
Are your houses council or private? I'm not being nosey by asking this, my thinking being that if they are council houses, could it be that your obnoxious neighbours have done this elsewhere and have simply been rehoused, which would only have the effect of moving the council's problem to another residence (if you follow that?).
It may well be that you will agree that a word from the Police to your neighbours may do the trick, but be prepared for your neighbours to make some counter allegation(s) against you, whether true or not. It's just human nature.
The council mediation service, which has been mentioned, is also one which I would ask you to consider, because it give you the chance to deal with someone independent who can sort of represent both parties and try to find some middle ground eventually leading to a long-term solution.